In telephones that are occasionally used by hearing-impaired persons, it is usually necessary to have a special amplifying arrangement that increases the receive level to a level that is convenient for the hearing-impaired persons.
Various arrangements have been used to help hearing impaired persons use a telephone. Well known, for example, has been a magnetic pickup coil connected to a hearing aid, which could be attached to a certain marked location on the handset and provide the hearing impaired person with a satisfactory hearing level.
Other arrangements are known, wherein a volume amplifier with a volume control dial is placed in the handset of a coin telephone and controls the gain of a hearing amplifier in the telephone circuit. Such volume controls are frequently vandalized and the dial broken off, and it has the further drawback that unless the volume control is turned down after use, the next user of the phone may have his eardrums blasted with an excessive sound level when the phone is answered.
It is therefore an object of the instant invention to provide a volume control for public telephones that is virtually vandal proof and returns to normal hearing level after use by a hearing-impaired person.